code: def test_largest_cc():
      """Check the extraction of the largest connected component."""
      a = np.zeros((6, 6, 6))
      a[1:3, 1:3, 1:3] = 1
      assert_array_equal(a, largest_cc(a))
      b = a.copy()
      b[5, 5, 5] = 1
      assert_array_equal(a, largest_cc(b))
  
file_path: nipy/nipy/labs/tests/test_mask.py
imports: import nibabel
  import numpy
  from nipy.testing import anatfile, assert_array_equal
  from ..None import mask
  from ..mask import largest_cc, series_from_mask, threshold_connect_components
label_desc: Use image node_id 1 for calling a global function with example usage: test_largest_cc() without return types